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Does anyone know how to remove this crank arm? Or if it can be removed? The bike was ~$250 and seems to have a lot of 'don't take this apart' engineering, I'd like to soak the chain rings in rust remover without the arm interfering. The interface is also just a bit loose. It's not clear if there's any way to tighten that gear-looking around the square.

Chain ring

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    There's not enough rust there to make it worth disassembling. Instead, apply some rust refixer like Phosphoric Acid (like "rustbuster") and then keep riding. The teeth look fine, so if you're getting transmission problems its time for a new chain and cassette.
    – Criggie ♦
    Jun 23, 2017 at 0:26
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    There's not much point as @Criggie says. To get that apart you'd need a load of heat and or a press. The heat would mess up the paint work and probably warp the chain rings if you got it wrong. I'd personally clean it off with some degreaser and some wet-n-dry sandpaper if the rust is bothering you. Get a bit of wd-40 or gt-85 on there to keep some moisture off and clean and re-lube the rest of the drivetrain.
    – Chris
    Jun 23, 2017 at 19:23

3 Answers 3

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Sorry, those chainrings are riveted in place. You just have to replace the whole crank arm.

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    And if you are going to replace it, you'll want to take the old one into a shop to make sure the new one is compatible. The main difference I'm thinking of is how far left or right the rings are in comparison to the crank. Otherwise you may need to get a different length bottom bracket to position the rings properly.
    – Noah Sutherland
    Jun 22, 2017 at 21:17
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    Noted. It really isn't worth the bother with this bike, though.
    – Alex
    Jun 22, 2017 at 23:47
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You could drill out the rivets (and later replace them with button-head hex screws) so that you could take off the chainrings. But this would be more effort than its worth. And it's not like you could easily find replacement chainrings anyway.

As @criggie notes, there's not nearly enough rust to make this worth it. Scrubbing the chainrings with chain cleaner and a brush should take off most of it. Those 'rust' marks are places where the chain abrades when the gears shift, any paint you put on them will be scraped off the next time you shift.

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It is possible the above responders may be missing the point. In this case the larger chainring and spider is a one piece combo. The question is the press fit of the pedal arm with the spider reversible and what is the procedure and tools required. Not sure, but if it is a part that has questionable safety status where in you have a concern that the part will no longer perform as designed, then it may be a candidate for experimentation.

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  • Could you clarify what you mean by missing the point? The OP was unfamiliar with the pictured square-taper style crankset with riveted chainrings and wanted to know if it was possible to disassemble it to clean the chainrings away from the crankarm. The answers indicated it wasn't designed for disassembly.
    – Armand
    Apr 16, 2021 at 22:00
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    @Armand it is a valid point. The question is asking about the crank arm to spider interface, while the answers discuss the spider to chainrings interface.
    – MaplePanda
    Apr 17, 2021 at 0:39
  • On re-reading, you're right. OP mentions both cleaning the chainrings , and tightening some looseness in the central interface (I presume thats between crank arm and the rest of the structure) Good spotting! However it doesn't significantly change the result of "it is rivetted together" and therefore not intended to be serviced, not that has stopped me before!
    – Criggie ♦
    Apr 17, 2021 at 10:02

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